The west facade was begun in the mid-thirteenth century, and was completed
up to the cornice above the portals around 1300. The portals stood in front
of a Romanesque nave until the present nave was begun in the early fourteenth
century. Nave construction proceeded slowly, and it was not until nearly
1500 that the facade was built higher to buttress the nave walls. While
the north tower was eventually completed, on the south only the masonry
necessary to enclose and buttress the nave was finished. The north tower
was completed in the 1540s, marking the end of medieval construction at
the cathedral.